Investment banking league tables rank investment banks on their level of involvement in specific types of transactions. An individual league table might, for example, rank the investment advisors of merger and Acquisition deals (usually by aggregate deal volume) and another might rank the underwriters of equity or fixed income offerings. some sources for this information include:

Bloomberg provides dynamic underwriter and legal league tables covering equity and debt offerings as well as mergers & acquisitions activity. You can use the Deal Monitor (DMON <GO>) to get a high level view of activity or you can go to deal type monitors. For Underwriters, use LEAG <GO>. For M&A Financial Advisors, use MA <GO>. Note that you can create custom searches and save them for faster recall at a later time. Some pre-made league tables are available online for free from the Bloomberg League Table page.

SDC Platinum, produced by Thomson Reuters, provide league tables and individual transaction information.

Capital IQ screening tool allows you to create league tables. Select Screening > Transactions and choose the specifics of your search. Note that you can save searches and set up email alerts to notify you when new deals happen.